我要评论input type=file 文件压缩
js 图片压缩 尺寸不变 压缩质量
<input type=“file” accept=“image/*” name=“files” @change=“imgMsgListDangerImgs”/>
imgMsgListDangerImgs(data) {
this.imageCompression(data.target.files[0], ‘1’)
},
//a 为flag位 可删 data 为input 获取的二进制文件
imageCompression: async function (data, a) {
let self = this;
let Orientation;
let ndata;
debugger
if (data.size <= 1 * 1024 * 1024) {
//判断图片是否大于1M,是就直接上传
ndata = data;
self.postImg(ndata, a);
} else {
//反之压缩图片
let reader = new FileReader();
// 将图片2将转成 base64 格式
reader.readAsDataURL(data);
console.log(reader)
// 读取成功后的回调
reader.onloadend = function () {
let result = this.result;
let img = new Image();
img.src = result;
img.onload = function () {
let data2 = self.compress(img, Orientation);
self.headerImage = data2;
ndata = self.compress(img, Orientation);
//BASE64转图片
var arr = ndata.split(','), mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
while (n--) {
u8arr[n] = bstr.charCodeAt(n);
}
ndata = new File([u8arr], data.name, {type: mime})
// return ndata
self.postImg(ndata, a);
}
}
}
},
compress(img, Orientation) {
let canvas = document.createElement("canvas");
let ctx = canvas.getContext('2d');
//瓦片canvas
let tCanvas = document.createElement("canvas");
let tctx = tCanvas.getContext("2d");
let initSize = img.src.length;
let width = img.width;
let height = img.height;
//如果图片大于四百万像素，计算压缩比并将大小压至400万以下
let ratio;
if ((ratio = width * height / 4000000) > 1) {
console.log("大于400万像素")
ratio = Math.sqrt(ratio);
width /= ratio;
height /= ratio;
} else {
ratio = 1;
}
canvas.width = width;
canvas.height = height;
// 铺底色
ctx.fillStyle = "#fff";
ctx.fillRect(0, 0, canvas.width, canvas.height);
//如果图片像素大于100万则使用瓦片绘制
let count;
if ((count = width * height / 1000000) > 1) {
console.log("超过100W像素");
count = ~~(Math.sqrt(count) + 1); //计算要分成多少块瓦片
// 计算每块瓦片的宽和高
let nw = ~~(width / count);
let nh = ~~(height / count);
tCanvas.width = nw;
tCanvas.height = nh;
for (let i = 0; i < count; i++) {
for (let j = 0; j < count; j++) {
tctx.drawImage(img, i * nw * ratio, j * nh * ratio, nw * ratio, nh * ratio, 0, 0, nw, nh);
ctx.drawImage(tCanvas, i * nw, j * nh, nw, nh);
}
}
} else {
ctx.drawImage(img, 0, 0, width, height);
}
//修复ios上传图片的时候 被旋转的问题
if (Orientation != "" && Orientation != 1) {
switch (Orientation) {
case 6://需要顺时针（向左）90度旋转
this.rotateImg(img, 'left', canvas);
break;
case 8://需要逆时针（向右）90度旋转
this.rotateImg(img, 'right', canvas);
break;
case 3://需要180度旋转
this.rotateImg(img, 'right', canvas);//转两次
this.rotateImg(img, 'right', canvas);
break;
}
}
//进行压缩
let ndata = canvas.toDataURL('image/jpeg', 0.1);
console.log('压缩前：' + initSize);
console.log('压缩后：' + ndata.length);
console.log("ndata:" + ndata)
console.log('压缩率：' + ~~(100 * (initSize - ndata.length) / initSize) + "%");
tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
return ndata;
},
async postImg(ndata, a) {
let mine = this;
let param = new FormData(); //创建form对象
param.append('file', ndata); //通过append向form对象添加数据
let config = {
headers: {
'Content-Type': 'multipart/form-data'
}
}
try {
// const response = await FileUpload(param, config) //此处写接口对应的vue方法
const res = await axios.post(FILE_URL, param, config);
//营业执照
if (a == '0') {
mine.businesslicense.push({
id: new Date().getTime(),
src: res.data,
type: "新",
});
mine.tshopVo.shopCheckInfo.businesslicense = JSON.stringify(mine.businesslicense);
}
} catch (error) {
console.log(error)
}
},
},
本文地址：https://blog.csdn.net/weixin_42752532/article/details/107936090
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